Without Stripe!

1. Row owner column

Because shopping cart must contains only specific user's items, we should set up the Row Owner ****column. To do this just add a new e-mail column and hit «Make row owner». Then put signed in user's e-mail in there.

2. Inline list

1. Item's name.
2. Image. In my example this is a Lookup column, but basically it can be just regular Image column. You can read more about Lookup columns as Image containers here.
3. Quantity. This is for quantity of the item. For some math reasons it must be Number column.
4. Cost. This is the basic calculation [quantity]*[item's price]. Math column.

3. Details view

You can configure it as you like. My way is below.

3. Total Cost

This is a Rollup column which calculates the sum of costs.

4. Empty Cart button